He also said if there is no deal, the UK would keep a “very substantial” part of the £39bn former prime minister Theresa May had agreed to pay the EU in her withdrawal agreement – the deal which British MPs rejected three times.

But, responding on Monday, European Commission spokeswoman Mina Andreeva said the UK must honour commitments made during its EU membership, and said this was “especially true in a no-deal scenario”.

She said that “settling accounts is essential to starting off a new relationship on the right foot”.

Guy Verhofstadt, the European Parliament’s Brexit co-ordinator, said: “If the UK doesn’t pay what is due, the EU will not negotiate a trade deal.”

The G7 summit – a get-together of most of the leaders of the world’s largest economies – comes with just over two months until the UK is scheduled to leave the EU.

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Media captionBoris Johnson: “In the last few days there’s been a sort of dawning realisation in Brussels and other European capitals”

The SNP, Liberal Democrats, Change UK, Plaid Cymru and the Green Party have all accepted the invitation to meet Mr Corbyn to discuss his proposals to avert a no-deal Brexit on Tuesday.

She said the discussions should examine how to seize control of Commons business, oust Mr Johnson and install an emergency “government of national unity”.

The Labour leader’s insistence on being interim leader meant there was a danger not enough MPs would support the vote, Ms Swinson said.

In a letter to Mr Corbyn, she said: “As you have said that you would do anything to avoid no deal, I hope you are open to a discussion about how conceding this point may open the door to a no-confidence vote succeeding. Its success must be the priority.”

Labour has not responded to the letter, but has instead referred to comments made by its shadow international trade secretary, Barry Gardiner, who on Sunday described Ms Swinson as “extremely petulant” for dismissing Mr Corbyn’s initial proposal.

Mr Corbyn has said he would call a no-confidence vote at the “earliest opportunity when we can be confident of success”. That cannot happen before 3 September, when MPs return from summer recess.

In order for such a vote to succeed, Labour would require support from across the House of Commons, including the Lib Dems, the SNP and Conservative rebels.